1. Area of the Art
The present invention relates to the art of producing coagulation factor concentrates from blood plasma.
The invention is directed to enhancing the yield and purity of fractionated plasma proteins.
2. Description of the Prior Art
There are a number of medical indications for administration of “clotting” or “coagulation” factors from human blood. These factors are proteins that cause the clotting of blood to staunch bleeding from wounds, etc. Individuals with any of a series of genetic abnormalities affecting the proteins responsible for blood coagulation are afflicted with a disease (hemophilia) in which the blood fails to clot normally, subjecting the individual to the danger of uncontrolled bleeding. For many years, this condition has been treated by administering concentrates of the missing or defective proteins. Many clotting factors are synthesized in the liver so that victims of liver disease are also in need of augmentation of their clotting factors. Additionally, there are other important medical uses for clotting-related factors including the use of fibrin to produce “fibrin sealant” or “fibrin glue” or “fibrin fabric”.
While some of the clotting factors are currently produced through biotechnology, at this time there is still no cost effective method of artificially manufacturing all of these proteins or these proteins in sufficient quantities. Further, the “artificially produced” factors made by recombinant and related technologies tend to be more expensive. Many of the “minor” factors are not yet (and may never be) available from biotechnology sources and so must be purified from donated human blood. Also, there is often a synergy between factors whereby a single administered recombinant factor is not nearly as effective as a natural mixed fraction produced from fractionated blood.
There is also a special problem in Third World countries where the biotechnology products are generally either not available or not affordable. Therefore, much of the supply of anti-hemophilia factor (AHF, also known as Factor VIII), and other blood clotting factors are prepared from pooled human plasma. A hemophiliac requires treatment for a whole lifetime. Victims of liver disease and other users of clotting factors may also require prolonged treatment. Therefore, these patients are exposed to blood products produced from the blood of a large number of donors.
The presence of AIDS (Acquired Immuno Deficiency Syndrome) virus or HIV in the blood supply means that hemophiliacs and other users of clotting factors have become infected with this terrible disease. Although tests to screen out AIDS-tainted blood have been improved, some infected blood does slip by. Even if the AIDS problem is solved, the danger of other blood-borne diseases, such as the various types of hepatitis and other, as yet unknown, infectious agents, makes it desirable to reduce or eliminate virus and other disease organisms from plasma used to prepare clotting factors. One way of achieving this goal is to replace pooled plasma products with products from a single donor (or pooled from a limited number of donors) since with pooled products “one bad apple spoils the entire barrel”, and the larger the number of donors in a pool, the greater the chance of “spoilage”.
Even with the use of clotting factors derived from a single donor, there is still danger. Even though tests may show the donor is free of known disease, the donor may be incubating a disease that will later show up on the tests, or the donor may harbor a yet unknown disease or a yet unknown strain of a known disease. These dangers have been lessened by use of plasma pre-treatments that inactivate disease organisms. Unfortunately, the best commonly used treatments either do not inactivate all types of disease organisms or damage the labile clotting factors during the process of inactivating disease organisms.
The basic methods for preparing clotting factor concentrates from blood have not changed greatly over the last few decades. Generally, a concentrate of clotting factors is derived from pooled plasma by a cryoprecipitation step. The plasma is frozen and then thawed. During the freezing process certain proteins precipitate to form a “cryoprecipitate.” Various additives such as ethanol and/or polyethylene glycol are often added to enhance the efficiency of the cryoprecipitation step. Following cryoprecipitation, the partially purified factors may be further purified by additional precipitation steps or by chromatographic methods, and most recently by methods using monoclonal antibodies. For additional information on the basic techniques of clotting factor purification and the history of the development of these methods, the reader is directed to U.S. Pat. Nos. 3,560,475, 3,631,018, 3,682,881, 4,069,216, and 4,305,871 and 5,770,704 by the present inventor, the contents of which are incorporated herein by reference, and the references cited therein. Because these and similar methods usually involve pools of plasma from many donors, the relative safety of a single or limited donor pool is generally not attained.
After the cryoprecipitate has been removed, the supernatant remaining is usually subjected to further purification by means of ethanol precipitation to yield gamma globulin (immune globulin) and albumin, both of which have significant uses in medicine. After the clotting factors have been purified from the cryoprecipitate, the leftover fibrinogen (including fibronectin and some other factors) is either discarded or used to produce some type of fibrin sealant or bandage.